KVM: nVMX: Fix some comment typos and coding style

Fix some typos in the comments. Also fix coding style.
[Sean Christopherson rewrites the comment of write_fault_to_shadow_pgtable
field in struct kvm_vcpu_arch.]

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4dffbc10d3f8..40a0c0fd95ca 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -781,9 +781,19 @@ struct kvm_vcpu_arch {
 	u64 msr_kvm_poll_control;
 
 	/*
-	 * Indicate whether the access faults on its page table in guest
-	 * which is set when fix page fault and used to detect unhandeable
-	 * instruction.
+	 * Indicates the guest is trying to write a gfn that contains one or
+	 * more of the PTEs used to translate the write itself, i.e. the access
+	 * is changing its own translation in the guest page tables.  KVM exits
+	 * to userspace if emulation of the faulting instruction fails and this
+	 * flag is set, as KVM cannot make forward progress.
+	 *
+	 * If emulation fails for a write to guest page tables, KVM unprotects
+	 * (zaps) the shadow page for the target gfn and resumes the guest to
+	 * retry the non-emulatable instruction (on hardware).  Unprotecting the
+	 * gfn doesn't allow forward progress for a self-changing access because
+	 * doing so also zaps the translation for the gfn, i.e. retrying the
+	 * instruction will hit a !PRESENT fault, which results in a new shadow
+	 * page and sends KVM back to square one.
 	 */
 	bool write_fault_to_shadow_pgtable;